/*

 * Copyright 2007-2009 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.nio.file.attribute;

import java.nio.file.*;

import java.io.IOException;

import java.util.*;

import java.util.concurrent.TimeUnit;

/**

 * This class consists exclusively of static methods that operate on or return

 * the attributes of files or file stores. These methods provide for convenient

 * use of the {@link AttributeView attribute-views} defined in this package.

 *

 * @since 1.7

 */

public final class Attributes {

    private Attributes() {

    }

    /**

     * Splits the given attribute name into the name of an attribute view and

     * the attribute. If the attribute view is not identified then it assumed

     * to be "basic".

     */

    private static String[] split(String attribute) {

        String[] s = new String[2];

        int pos = attribute.indexOf(':');

        if (pos == -1) {

            s[0] = "basic";

            s[1] = attribute;

        } else {

            s[0] = attribute.substring(0, pos++);

            s[1] = (pos == attribute.length()) ? "" : attribute.substring(pos);

        }

        return s;

    }

    /**

     * Sets the value of a file attribute.

     *

     * <p> The {@code attribute} parameter identifies the attribute to be set

     * and takes the form:

     * <blockquote>

     * [<i>view-name</i><b>:</b>]<i>attribute-name</i>

     * </blockquote>

     * where square brackets [...] delineate an optional component and the

     * character {@code ':'} stands for itself.

     *

     * <p> <i>view-name</i> is the {@link FileAttributeView#name name} of a {@link

     * FileAttributeView} that identifies a set of file attributes. If not

     * specified then it defaults to {@code "basic"}, the name of the file

     * attribute view that identifies the basic set of file attributes common to

     * many file systems. <i>attribute-name</i> is the name of the attribute

     * within the set.

     *

     * <p> <b>Usage Example:</b>

     * Suppose we want to set the DOS "hidden" attribute:

     * <pre>

     *    Attributes.setAttribute(file, "dos:hidden", true);

     * </pre>

     *

     * @param   file

     *          A file reference that locates the file

     * @param   attribute

     *          The attribute to set

     * @param   value

     *          The attribute value

     *

     * @throws  UnsupportedOperationException

     *          If the attribute view is not available or it does not

     *          support updating the attribute

     * @throws  IllegalArgumentException

     *          If the attribute value is of the correct type but has an

     *          inappropriate value

     * @throws  ClassCastException

     *          If the attribute value is not of the expected type or is a

     *          collection containing elements that are not of the expected

     *          type

     * @throws  IOException

     *          If an I/O error occurs

     * @throws  SecurityException

     *          In the case of the default provider, and a security manager is

     *          installed, its {@link SecurityManager#checkWrite(String) checkWrite}

     *          method denies write access to the file. If this method is invoked

     *          to set security sensitive attributes then the security manager

     *          may be invoked to check for additional permissions.

     */

    public static void setAttribute(FileRef file, String attribute, Object value)

        throws IOException

    {

        String[] s = split(attribute);

        FileAttributeView view = file.getFileAttributeView(s[0]);

        if (view == null)

            throw new UnsupportedOperationException("View '" + s[0] + "' not available");

        view.setAttribute(s[1], value);

    }

    /**

     * Reads the value of a file attribute.

     *

     * <p> The {@code attribute} parameter identifies the attribute to be read

     * and takes the form:

     * <blockquote>

     * [<i>view-name</i><b>:</b>]<i>attribute-name</i>

     * </blockquote>

     * where square brackets [...] delineate an optional component and the

     * character {@code ':'} stands for itself.

     *

     * <p> <i>view-name</i> is the {@link FileAttributeView#name name} of a {@link

     * FileAttributeView} that identifies a set of file attributes. If not

     * specified then it defaults to {@code "basic"}, the name of the file

     * attribute view that identifies the basic set of file attributes common to

     * many file systems. <i>attribute-name</i> is the name of the attribute.

     *

     * <p> The {@code options} array may be used to indicate how symbolic links

     * are handled for the case that the file is a symbolic link. By default,

     * symbolic links are followed and the file attribute of the final target

     * of the link is read. If the option {@link LinkOption#NOFOLLOW_LINKS

     * NOFOLLOW_LINKS} is present then symbolic links are not followed and so

     * the method returns the file attribute of the symbolic link.

     *

     * <p> <b>Usage Example:</b>

     * Suppose we require the user ID of the file owner on a system that

     * supports a "{@code unix}" view:

     * <pre>

     *    int uid = (Integer)Attributes.getAttribute(file, "unix:uid");

     * </pre>

     *

     * @param   file

     *          A file reference that locates the file

     * @param   attribute

     *          The attribute to read

     * @param   options

     *          Options indicating how symbolic links are handled

     *

     * @return  The attribute value, or {@code null} if the attribute view

     *          is not available or it does not support reading the attribute

     *

     * @throws  IOException

     *          If an I/O error occurs

     * @throws  SecurityException

     *          In the case of the default provider, and a security manager is

     *          installed, its {@link SecurityManager#checkRead(String) checkRead}

     *          method denies read access to the file. If this method is invoked

     *          to read security sensitive attributes then the security manager

     *          may be invoked to check for additional permissions.

     */

    public static Object getAttribute(FileRef file,

                                      String attribute,

                                      LinkOption... options)

        throws IOException

    {

        String[] s = split(attribute);

        FileAttributeView view = file.getFileAttributeView(s[0], options);

        if (view != null)

            return view.getAttribute(s[1]);

        // view not available

        return null;

    }

    /**

     * Reads a set of file attributes as a bulk operation.

     *

     * <p> The {@code attributes} parameter identifies the attributes to be read

     * and takes the form:

     * <blockquote>

     * [<i>view-name</i><b>:</b>]<i>attribute-list</i>

     * </blockquote>

     * where square brackets [...] delineate an optional component and the

     * character {@code ':'} stands for itself.

     *

     * <p> <i>view-name</i> is the {@link FileAttributeView#name name} of a {@link

     * FileAttributeView} that identifies a set of file attributes. If not

     * specified then it defaults to {@code "basic"}, the name of the file

     * attribute view that identifies the basic set of file attributes common to

     * many file systems.

     *

     * <p> The <i>attribute-list</i> component is a comma separated list of

     * zero or more names of attributes to read. If the list contains the value

     * {@code "*"} then all attributes are read. Attributes that are not supported

     * are ignored and will not be present in the returned map. It is

     * implementation specific if all attributes are read as an atomic operation

     * with respect to other file system operations.

     *

     * <p> The following examples demonstrate possible values for the {@code

     * attributes} parameter:

     *

     * <blockquote>

     * <table border="0">

     * <tr>

     *   <td> {@code "*"} </td>

     *   <td> Read all {@link BasicFileAttributes basic-file-attributes}. </td>

     * </tr>

     * <tr>

     *   <td> {@code "size,lastModifiedTime,lastAccessTime"} </td>

     *   <td> Reads the file size, last modified time, and last access time

     *     attributes. </td>

     * </tr>

     * <tr>

     *   <td> {@code "posix:*"} </td>

     *   <td> Read all {@link PosixFileAttributes POSIX-file-attributes}.. </td>

     * </tr>

     * <tr>

     *   <td> {@code "posix:permissions,owner,size"} </td>

     *   <td> Reads the POSX file permissions, owner, and file size. </td>

     * </tr>

     * </table>

     * </blockquote>

     *

     * <p> The {@code options} array may be used to indicate how symbolic links

     * are handled for the case that the file is a symbolic link. By default,

     * symbolic links are followed and the file attributes of the final target

     * of the link are read. If the option {@link LinkOption#NOFOLLOW_LINKS

     * NOFOLLOW_LINKS} is present then symbolic links are not followed and so

     * the method returns the file attributes of the symbolic link.

     *

     * @param   file

     *          A file reference that locates the file

     * @param   attributes

     *          The attributes to read

     * @param   options

     *          Options indicating how symbolic links are handled

     *

     * @return  A map of the attributes returned; may be empty. The map's keys

     *          are the attribute names, its values are the attribute values

     *

     * @throws  IOException

     *          If an I/O error occurs

     * @throws  SecurityException

     *          In the case of the default provider, and a security manager is

     *          installed, its {@link SecurityManager#checkRead(String) checkRead}

     *          method denies read access to the file. If this method is invoked

     *          to read security sensitive attributes then the security manager

     *          may be invoke to check for additional permissions.

     */

    public static Map<String,?> readAttributes(FileRef file,

                                               String attributes,

                                               LinkOption... options)

        throws IOException

    {

        String[] s = split(attributes);

        FileAttributeView view = file.getFileAttributeView(s[0], options);

        if (view != null) {

            // further split attributes into the first and rest.

            String[] names = s[1].split(",");

            int rem = names.length-1;

            String first = names[0];

            String[] rest = new String[rem];

            if (rem > 0) System.arraycopy(names, 1, rest, 0, rem);

            return view.readAttributes(first, rest);

        }

        // view not available

        return Collections.emptyMap();

    }

    /**

     * Reads the basic file attributes of a file.

     *

     * <p> The {@code options} array may be used to indicate how symbolic links

     * are handled for the case that the file is a symbolic link. By default,

     * symbolic links are followed and the file attributes of the final target

     * of the link are read. If the option {@link LinkOption#NOFOLLOW_LINKS

     * NOFOLLOW_LINKS} is present then symbolic links are not followed and so

     * the method returns the file attributes of the symbolic link. This option

     * should be used where there is a need to determine if a file is a

     * symbolic link:

     * <pre>

     *    boolean isSymbolicLink = Attributes.readBasicFileAttributes(file, NOFOLLOW_LINKS).isSymbolicLink();

     * </pre>

     *

     * <p> It is implementation specific if all file attributes are read as an

     * atomic operation with respect to other file system operations.

     *

     * @param   file

     *          A file reference that locates the file

     * @param   options

     *          Options indicating how symbolic links are handled

     *

     * @return  The basic file attributes

     *

     * @throws  IOException

     *          If an I/O error occurs

     * @throws  SecurityException

     *          In the case of the default provider, the security manager's {@link

     *          SecurityManager#checkRead(String) checkRead} method is invoked

     *          to check read access to file

     *

     * @see BasicFileAttributeView#readAttributes

     */

    public static BasicFileAttributes readBasicFileAttributes(FileRef file,

                                                              LinkOption... options)

        throws IOException

    {

        return file.getFileAttributeView(BasicFileAttributeView.class, options)

            .readAttributes();

    }

    /**

     * Reads the POSIX file attributes of a file.

     *

     * <p> The {@code file} parameter locates a file that supports the {@link

     * PosixFileAttributeView}. This file attribute view provides access to a

     * subset of the file attributes commonly associated with files on file

     * systems used by operating systems that implement the Portable Operating

     * System Interface (POSIX) family of standards. It is implementation

     * specific if all file attributes are read as an atomic operation with

     * respect to other file system operations.

     *

     * <p> The {@code options} array may be used to indicate how symbolic links

     * are handled for the case that the file is a symbolic link. By default,

     * symbolic links are followed and the file attributes of the final target

     * of the link are read. If the option {@link LinkOption#NOFOLLOW_LINKS

     * NOFOLLOW_LINKS} is present then symbolic links are not followed and so

     * the method returns the file attributes of the symbolic link.

     *

     * @param   file

     *          A file reference that locates the file

     * @param   options

     *          Options indicating how symbolic links are handled

     *

     * @return  The POSIX file attributes

     *

     * @throws  UnsupportedOperationException

     *          If the {@code PosixFileAttributeView} is not available

     * @throws  IOException

     *          If an I/O error occurs

     * @throws  SecurityException

     *          In the case of the default provider, and a security manager is

     *          installed, it denies {@link RuntimePermission}<tt>("accessUserInformation")</tt>

     *          or its {@link SecurityManager#checkRead(String) checkRead} method

     *          denies read access to the file.

     *

     * @see PosixFileAttributeView#readAttributes

     */

    public static PosixFileAttributes readPosixFileAttributes(FileRef file,

                                                              LinkOption... options)

        throws IOException

    {

        PosixFileAttributeView view =

            file.getFileAttributeView(PosixFileAttributeView.class, options);

        if (view == null)

            throw new UnsupportedOperationException();

        return view.readAttributes();

    }

    /**

     * Reads the DOS file attributes of a file.

     *

     * <p> The {@code file} parameter locates a file that supports the {@link

     * DosFileAttributeView}. This file attribute view provides access to

     * legacy "DOS" attributes supported by the file systems such as File

     * Allocation Table (FAT), commonly used in <em>consumer devices</em>. It is

     * implementation specific if all file attributes are read as an atomic

     * operation with respect to other file system operations.

     *

     * <p> The {@code options} array may be used to indicate how symbolic links

     * are handled for the case that the file is a symbolic link. By default,

     * symbolic links are followed and the file attributes of the final target

     * of the link are read. If the option {@link LinkOption#NOFOLLOW_LINKS

     * NOFOLLOW_LINKS} is present then symbolic links are not followed and so

     * the method returns the file attributes of the symbolic link.

     *

     * @param   file

     *          A file reference that locates the file

     * @param   options

     *          Options indicating how symbolic links are handled

     *

     * @return  The DOS file attributes

     *

     * @throws  UnsupportedOperationException

     *          If the {@code DosFileAttributeView} is not available

     * @throws  IOException

     *          If an I/O error occurs

     * @throws  SecurityException

     *          In the case of the default provider, the security manager's {@link

     *          SecurityManager#checkRead(String) checkRead} method is invoked

     *          to check read access to file

     *

     * @see DosFileAttributeView#readAttributes

     */

    public static DosFileAttributes readDosFileAttributes(FileRef file,

                                                          LinkOption... options)

        throws IOException

    {

        DosFileAttributeView view =

            file.getFileAttributeView(DosFileAttributeView.class, options);

        if (view == null)

            throw new UnsupportedOperationException();

        return view.readAttributes();

    }

    /**

     * Returns the owner of a file.

     *

     * <p> The {@code file} parameter locates a file that supports the {@link

     * FileOwnerAttributeView}. This file attribute view provides access to

     * a file attribute that is the owner of the file.

     *

     * @param   file

     *          A file reference that locates the file

     *

     * @return  A user principal representing the owner of the file

     *

     * @throws  UnsupportedOperationException

     *          If the {@code FileOwnerAttributeView} is not available

     * @throws  IOException

     *          If an I/O error occurs

     * @throws  SecurityException

     *          In the case of the default provider, and a security manager is

     *          installed, it denies {@link RuntimePermission}<tt>("accessUserInformation")</tt>

     *          or its {@link SecurityManager#checkRead(String) checkRead} method

     *          denies read access to the file.

     *

     * @see FileOwnerAttributeView#getOwner

     */

    public static UserPrincipal getOwner(FileRef file) throws IOException {

        FileOwnerAttributeView view =

            file.getFileAttributeView(FileOwnerAttributeView.class);

        if (view == null)

            throw new UnsupportedOperationException();

        return view.getOwner();

    }

    /**

     * Updates the file owner.

     *

     * <p> The {@code file} parameter locates a file that supports the {@link

     * FileOwnerAttributeView}. This file attribute view provides access to

     * a file attribute that is the owner of the file.

     *

     * @param   file

     *          A file reference that locates the file

     * @param   owner

     *          The new file owner

     *

     * @throws  UnsupportedOperationException

     *          If the {@code FileOwnerAttributeView} is not available

     * @throws  IOException

     *          If an I/O error occurs

     * @throws  SecurityException

     *          In the case of the default provider, and a security manager is

     *          installed, it denies {@link RuntimePermission}<tt>("accessUserInformation")</tt>

     *          or its {@link SecurityManager#checkWrite(String) checkWrite}

     *          method denies write access to the file.

     *

     * @see FileOwnerAttributeView#setOwner

     */

    public static void setOwner(FileRef file, UserPrincipal owner)

            throws IOException

    {

        FileOwnerAttributeView view =

            file.getFileAttributeView(FileOwnerAttributeView.class);

        if (view == null)

            throw new UnsupportedOperationException();

        view.setOwner(owner);

    }

    /**

     * Reads a file's Access Control List (ACL).

     *

     * <p> The {@code file} parameter locates a file that supports the {@link

     * AclFileAttributeView}. This file attribute view provides access to ACLs

     * based on the ACL model specified in

     *  <a href="http://www.ietf.org/rfc/rfc3530.txt"><i>RFC&nbsp;3530</i></a>.

     *

     * @param   file

     *          A file reference that locates the file

     *

     * @return  An ordered list of {@link AclEntry entries} representing the

     *          ACL. The returned list is modifiable.

     *

     * @throws  UnsupportedOperationException

     *          If the {@code AclAttributeView} is not available

     * @throws  IOException

     *          If an I/O error occurs

     * @throws  SecurityException

     *          In the case of the default provider, and a security manager is

     *          installed, it denies {@link RuntimePermission}<tt>("accessUserInformation")</tt>

     *          or its {@link SecurityManager#checkRead(String) checkRead} method

     *          denies read access to the file.

     *

     * @see AclFileAttributeView#getAcl

     */

    public static List<AclEntry> getAcl(FileRef file) throws IOException {

        AclFileAttributeView view =

            file.getFileAttributeView(AclFileAttributeView.class);

        if (view == null)

            throw new UnsupportedOperationException();

        return view.getAcl();

    }

    /**

     * Updates a file's Access Control List (ACL).

     *

     * <p> The {@code file} parameter locates a file that supports the {@link

     * AclFileAttributeView}. This file attribute view provides access to ACLs

     * based on the ACL model specified in

     *  <a href="http://www.ietf.org/rfc/rfc3530.txt"><i>RFC&nbsp;3530</i></a>.

     *

     * @param   file

     *          A file reference that locates the file

     * @param   acl

     *          The new file ACL